The light-emitting mechanism of the light-emitting diode is to take advantage of the energy difference of electrons between the n-type semiconductor and the p-type semiconductor and then to release the energy in the form of light, which is different from the light-emitting mechanism of the incandescent lamp, which is by heating. Therefore, the light-emitting diode is called the cold light source. Besides, the light-emitting diode has the advantages such as long endurance, long lifetime, light weight, and low power consumption. Therefore, the present illumination market expects the light-emitting diode as a new generation illumination to substitute for the traditional light source and apply it to various fields such as traffic signal, backlight module, street light, and medical apparatus.
FIG. 1 is the illustration of a conventional AC light-emitting diode device. As shown in FIG. 1, the light-emitting device 100 comprises a substrate 10, a plurality of light-emitting units 12 disposing on the substrate 10 and are serially connected to form circuit A and circuit B that are anti-parallel connected to each other later, and two electrodes 14 and 16 disposing on the substrate 10 and electrically connecting to the plurality of the light-emitting units 12. When the alternative current flows into the light-emitting device 100 through the electrode 14, the current passes through circuit A and triggers the light-emitting unit 12 in the circuit A to emit light. Correspondingly, when the alternative current flows into the light-emitting device 100 through the electrode 16, the current passes through circuit B and triggers the light-emitting unit 12 in the circuit B to emit light.
Besides, the light-emitting device 100 could form a photoelectric apparatus by further connecting with other components. FIG. 2 is the illustration for the conventional photoelectric apparatus. As shown in FIG. 2, a photoelectric apparatus 200 comprises a sub-mount 20, which comprises at least one circuit 202; a solder 22 located on the sub-mount 20 to attach the light-emitting device 100 on the sub-mount 20 and to electrically connect the substrate 10 of the light-emitting device 100 with the circuit 202 on the sub-mount 20; and one electrically connecting structure 24 electrically connecting the electrode 16 of the light-emitting device 100 and the circuit 202 on the sub-mount 20. The sub-mount 20 comprises a lead frame or a large-size mounting substrate to facilitate the circuit arrangement and to raise the heat dissipating efficiency.
Nevertheless, although the design of the light-emitting device 100 could be applied to the alternative current directly, only parts of the light-emitting units 12 emitting light at the same time often causes the waste of the light-emitting area on the light-emitting device.